Strange problems with my '88 2.9l

ranger306ci · Mar 22, 2010

Well, I searched through and could not find anyone else with my problem.
First of all, it is an 88 BII with 2.9 and A4LD.
My truck acts like it is losing gas sometimes while I am driving it.
The frustrating thing is the engine will do it warm or cold, at idle or under load, or even at just cruising speed.
It does it very sporadically, though. The engine will be going fine, and then it just starts sputtering. If I let it go long enough, it dies. Every now and then it bucks, or just flat out dies.
When it occurs, I turn the key off and back on really quick, and it will run fine for 30 seconds, or 30 miles.

codes pulled are ECT out of self check range, and O2 out of range.
Fuel pressure is fine while it is running fine, have not been
able to check it while it is acting up.
I have not replaced anything yet, I hate the shotgun approach to repair.

Planning on replacing O2 and ect, will be checking the grounds. Will replace the fuel filters ( most likely due anyways)
I plan on doing this one at a time, checking how each thing affects the problem.
Any other ideas?

notwb2 · Mar 24, 2010

Mine had kind of a similar problem. Mine turned out to be the connection that attaches to the inertia switch starting to go bad. I was getting some of you symptoms over a period of time. Try disconnecting the harness part of the switch and see if it is that. I bridged a paper clip from one side of the plug in the the other (to bypass the actual inertia/fuel cutoff switch). It is located on the passenger side foot area just under the lip of carpet. Hope this helps

88_Eddie · Mar 24, 2010

i sort of had this same problem with my exploder. ended up being a bad plug wire, i'd check them and def change the fuel filter, it's easy and cheap. if that doesnt work then i'd do the ECT (btw, you mean the sensor or sender?) and then the o2. the o2 will def be the most expensive....about $40 at autozone

adsm08 · Mar 24, 2010

O2 sensor. I had this problem too (and admittedly those symptoms can be caused by a wide range of things) and found my O2 sensor had fallen apart.

You have an O2 sensor code, so that would by first place to check. I'd guess you probably did the test with the engine cold? That would explain the ECT sensor code.

jhammel85 · Mar 25, 2010

It sounds like a bad O2. If you really want to, try driving it a short distance with the O2 unplugged. Sometime in your drive you'll have it bog down quite a bit. It pretty much will run like crap the whole time!

foss40z · Mar 25, 2010

Mine was the high pressure fuel pump, did the exact same thing until the fuel pump completely died. Get the Bucking, and shutting off and stuttering sensation.

master hec0 · Mar 25, 2010

adsm08 said:
O2 sensor. I had this problem too (and admittedly those symptoms can be caused by a wide range of things) and found my O2 sensor had fallen apart.

You have an O2 sensor code, so that would by first place to check. I'd guess you probably did the test with the engine cold? That would explain the ECT sensor code.

ranger306ci · Mar 26, 2010

well, I went to change out the o2 sensor last night. Darn thing is in a real nasty spot, with the tranny cooling lines right up against it. Abandoned efforts before collateral damage occurred. going down to my buddies shop today, we will either get it out, or drill an weld on a new bung in a better to access location.
If this does not fix it, I will keep looking. while it is in the air, the fuel filter will get changed out, and underneath wires inspected.
I did the code pulling per the manual, with the engine warm. I have an 89' I can pull sensors off for checking/ replacing. It has a good set of msd wires on it also, may throw them on, just make sure I do things one at a time until I find the problem!
Thanks for replies; I have been leaning toward hp fuel pump, but we will see what the o2 does.\

jhammel85 · Mar 26, 2010

I had a hard time with my O2 as well. Just soak it in some PB blaster or Kroil and be sure to use the right size wrench...Definitely don't want to strip it out!

When I did mine, I stripped it on accident. It was the angle and the fact that I was not using the right tool for the job. That's what I get for rushing in the cold!!
I cut mine out @ the bung and rewelded it back up. worked fine, looks fine, still works fine with no leaks BUT it would of been a much better job, IMO, if the pipe was brought down.

You might want to try to bring down that pipe if need be. Just go easy on those rusty bolts that go to the manifold. It wont take much to break them.

Also it sounds like you are thinking about relocating the O2 sensor? If you are thinking about doing that, I don't think I would. It can throw off the computer and how the O2 reads. Its in a specific spot for a reason. It might make matters worse.

Good Luck!

lethal-threat-b288 · Mar 30, 2010

mine does the exact same thing. let me know how the o2 sensor thing goes so i know what to do with mines

ranger306ci · Mar 30, 2010

OK, I have driven it 3 times now with a new O2 sensor, and the truck is behaving fine!
That is so weird that the O2 sensor would affect it in open loop. And to such an extent!

As for relocating it; I did. I only moved it about 1" down the pipe, and it is now horizontal, instead of vertical.
The old sensor is still on the pipe, I will remove it when I replace the cats at some point this summer.
I am still trying to figure out how the O2 sensor was failing in such a way to effectively kill the engine.
This is kinda strange too; I drove it into town with the old O2 unplugged (and the new one not on yet) and it ran fine for me. So moral is no o2 is better than a bad o2 sometimes !

Thanks for the help!

lethal-threat-b288 · Mar 30, 2010

how much did the sensor run you?

retep88 · Mar 31, 2010

The computer tries to auto-tune the engine using the O2 sensor to compensate for age and wear. If the computer was trying to tune the engine with the bad O2, it would mess with the open loop. My engine was running bad b/c of an O2 sensor and I had to unplug the computer for 5 minutes or so to reset the computer back to factory once I replace the bad O2.

Strange problems with my '88 2.9l

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